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An analysis of the effects of temperatures and circulations on the strength of the low-level jet in the Turkana Channel in East Africa

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Abstract

The Turkana Low-Level Jet (LLJ) was discovered in the early 1980s, yet there are still questions about the primary forcing mechanisms that drive and sustain the jet throughout the year. A few studies have addressed these questions, but most focus on numerical simulations of mechanical forcing mechanisms, such as orography, channeling flow, and monsoon background flow. No studies have shown the effects of thermal forcing from differential heating in the regions in and around the Turkana Channel. This paper uses National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) data and the National Aeronautics and Space Administration (NASA) Modern-Era Retrospective Analysis for Research and Applications (MERRA) data in order to analyze and find relationships between temperature gradients and the strength of the Turkana LLJ. In addition to temperature, potential temperature, divergence, wind magnitude, wind fields, and vertical motion are also examined. This analysis attempts to show that thermal forcing is one of the most important factors, if not the primary factor, in the initiation and maintenance of the jet and propose that more research and model simulations should be implemented to determine the contributions from thermal forcing.

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Acknowledgements

This study was supported by the National Science Foundation, AGS-1158984, and is a part of From Flood to Famine: The Rainfall Regime in East Africa, Its Interannual Variability, and Large-Scale Teleconnections. The assistance and guidance of Dr. Sharon E. Nicholson and Douglass Klotter are very much appreciated. Their suggestions and insight were vital to this manuscript.

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  1. Department of Earth, Ocean, and Atmospheric Sciences, Florida State University, Tallahassee, FL, USA

    Adam T. Hartman

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  1. Adam T. Hartman
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Correspondence to Adam T. Hartman.

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Hartman, A.T. An analysis of the effects of temperatures and circulations on the strength of the low-level jet in the Turkana Channel in East Africa. Theor Appl Climatol 132, 1003–1017 (2018). https://doi.org/10.1007/s00704-017-2121-x

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  • DOI: https://doi.org/10.1007/s00704-017-2121-x

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